Recently, a wireless local area network (LAN) function has been installed in an electronic device such as a digital camera and a printer in many cases. Thus, the electronic device is used as a communication device connected to a wireless LAN to be used. For example, a method of installing the wireless LAN function in a digital camera to facilitate image sharing is discussed in Japanese Patent Application Laid-Open No. 2009-152689.
Wi-Fi Alliance has defined a standard, Wi-Fi Direct (registered trademark). In Wi-Fi Direct (hereinafter, referred to as WFD), a protocol for determining whether each of electric devices operates as a wireless LAN access point or a wireless LAN station is defined. By executing the protocol, an electronic device that operates as the wireless LAN access point and an electric device that operates as the wireless LAN station can be automatically determined. With WFD, the electric devices can directly communicate with each other to execute various services (image sharing and printing, for example) without additionally preparing an access point. Thus, high usability is achieved.
When the WFD protocol is executed, a device uses a probe request signal and a probe response signal, as a search request signal and a search response signal defined in IEEE 802.11 standard, to detect a partner device that can execute the protocol.
More specifically, the device executing the WFD protocol (hereinafter, referred to as WFD execution device) transmits the probe request signal and the probe response signal with an information element for WFD as extended information.
The WFD execution device exchanges the probe signal having the additional information element with another WFD execution device. Thus, the partner devices that can execute the WFD protocol can identify each other.
The WFD execution device replies also to a device that is not executing WFD (hereinafter, referred to as non-WFD execution device) by sending the probe response signal, when receiving the probe request signal transmitted from the non-WFD execution device.
Thus, when the non-WFD execution device executing normal wireless LAN scanning processing for searching for a communication destination and the WFD execution device coexist, the non-WFD execution device receives the probe response signal from the WFD execution device.
Thus, the WFD execution device is displayed as a destination candidate on a user interface (UI) of the non-WFD execution device, and a user might accidently select the WFD execution device as the connection destination. As a result, a connection request is transmitted from the non-WFD execution device to the WFD execution device. Such a connection is never established, and thus the user has to reselect the connection destination. Therefore, the usability is low.
In the environment where the WFD execution device and the non-WFD execution device coexist, the non-WFD execution device transmits the probe response signal in response to the probe request signal transmitted from the WFD executing device. Thus, the WFD execution device receives the probe response signal from the non-WFD execution device. Specifically, the WFD execution device hoping to establish a connection with another WFD execution device receives the probe response signal from an unwanted non-WFD execution device.
Thus, the WFD execution device unnecessarily processes the probe response signal from the unwanted non-WFD execution device.
The WFD execution device transmits the probe response signal in response to the probe request signal transmitted from the non-WFD execution device. The non-WFD execution device that has received the probe response signal cannot identify the transmission source as the WFD execution device, and might cause the user to select the WFD execution device as the candidate of the connection destination. As a result, the connection request is transmitted from the non-WFD execution device to the WFD execution device. The connection might not be established due to the lack of capability to execute the WFD protocol. Thus, the processing needs to return to the processing of searching for a communication destination. Therefore, the usability is low.
As described above, in the conventional detection method using the probe signals, the unnecessary processing is executed in the environment where a device that executes certain processing and a device that does not execute the processing, for example, the WFD execution device and the non-WFD execution device, coexist.